Protective system for basic oxygen furnace lance

ABSTRACT

A system for automatically and positively retracting a basic oxygen furnace lance upon the occurrence of a power failure. The system is mechanical, relying only on gravity to withdraw the lance, and eliminates the necessity for auxiliary standby electrical and/or pneumatic equipment normally used to withdraw the lance when a power failure occurs.

United States Patent y l ['1 3,647,198

Munson 1 Mar. 7, 1972 [54] PROTECTIVE SYSTEM FOR BASIC gBBT liierences W OXYGEN FURNACE LANCE 'N'n- S A EN 1 lnvemofl William A-Munwmwilliwnsville, 3,201,103 8/1965 Scherff Q. ..266I34 LM [73] Assignee: Electric Corporation, Pitt- Primary Emminer4erald A'Dost Attorney-F. H. Henson and R. o. Brodahl [22] Filed: Aug. 17, 1970 21] Appl. No.: 64,445 ABSTRACT oxygen furnace lance upon the occurrence of a power failure.

A system for automatically and positively retracting a basic [52] US. Cl. ..266/34 LM 4 [51] (21 7/00 gelsystem isdmelchanlcal, trglymg onlzyon gram;i to may e ance, an (2 lmina 68 e necessl OI aux: ary S y [58] Field of Search ..266/34 L, 34 LM electrical and/or pneumafic equipment normally used to withdraw the lance when a power failure occurs.

9 Claims, 2 Drawing Figures o o I 56 A la 24 f k SUPPLY 4 E11: 3:3: I 53J PROTECTIVE SYSTEM FOR BASIC OXYGEN FURNACE LANCE BACKGROUND OF THE INVENTION As is known, the basic oxygen process for making steel is carried out in a vessel having the general resemblance of a Bessemer converter which is charged with molten pig iron and scrap. A water-cooled pipe called a lance is lowered through a hood, which covers the open top of the vessel, and into the converter to a point where the nozzle of the lance is relatively close to the molten metal. Oxygen under pressure is conveyed through the lance and onto the surface of the molten metal in the vessel to effect oxidation of impurities.

When the lance is inserted into the open end of the vessel and its end is slightly above the surface of the molten metal, oxygen and cooling water must be supplied to the lance since otherwise it will become damaged or possibly destroyed due to the intense heat of the molten metal. Failure of the oxygen or water supply can occur for various reasons; however it is quite likely that it will occur due to a failure of the electrical system which controls the flow of oxygen and water to the lance, as when a major electrical power failure occurs.

It is apparent that when there is a failure of oxygen and water flow, the lance must be withdrawn from the vessel rapidly. Most oxygen lance hoist systems depend upon either electrical devices for retracting the lance in the event of cooling water and oxygen flow failure or retraction by means of a compressed air-driven motor. When using electrical retraction, the system is dependent upon electrical power being available. The compressed air system also depends upon electrical power as the source of air compression.

To prevent loss of lance retraction power, when using electrical systems only, elaborate transfer schemes together with standby equipment are used to prevent loss of drive power in the even of a main electrical system failure. For compressed air backup, large compressed air storage tanks are required with enough capacity to permit lance extraction in the case of an emergency.

SUMMARY OF THE INVENTION In accordance with the present invention, a foolproof system is provided for automatically retracting a water-cooled oxygen lance from a basic'oxygen converter by the use of a falling weight dependent only upon gravity. The lance is connected to a flexible hoist line which passes around rotary sheave devices and usually along a straight-line reach to a driven drum connected to a drive motor. Specifically, the apparatus of the invention includes a weight connected to a sheave device which engages'and is on one side of the hoist line at a point along its length. The weight is of sufficient mass to cause the sheave device to move downwardly and elevate the lance when the aforesaid drum is braked and prevented from rotating. Normally, latch means holds the weight and its associated sheave device in an elevated position; however, when an electrical power failure occurs, apparatus is provided for unlatching the latch means while at the same time braking the drum against rotation whereby the lance will be elevated as the weight and its sheave device fall.

Preferably, the means for braking the drum comprises an electromagnetic brake which is automatically engaged upon a power failure, while the aforesaid latch means which holds the weight in an elevated position is held in its latched position by an electrical solenoid or the like which will become deenergized upon the occurrence of a power failure, thereby unlatching the weight and permitting it to fall to elevate the lance.

The above and other objects and features of the invention willbecome apparent from the following detailed description taken in connection with the accompanying drawings in which:

FIG. 1 is a schematic illustration of one embodiment of the invention; and

FIG. 2 is a fragmentary illustration of another embodiment of the invention.

With reference now' to FIG. 1, the system shown includes a basic oxygen converter comprising a refractory-linedvessel 10 which receives a bath 12 of molten metal to be refined. The vessel 10 is provided with an open top 14 over which is positioned a removable hood 16 which collects the gaseous products of combustion during the, refining process and conducts them to a stack or the like.

Extending downwardly into the open'mouth 14 of the vessel 10 is an oxygen lance 18 comprising an inner conduit which conveys oxygen down onto the surface of the bath 12 and a surrounding cooling chamber. The inner oxygen conduit is connected-to a flexible oxygen supply line'20, while the cooling chamber is connected to inlet and outlet flexible hoses v22 and 24, respectively, which conduct a supply of circulating cooling water to the lance 18.

The upper end of the lance 18 is connectedgto a cable 26 which, in turn, passes around sheaves 28 and 30 to a drum 32 driven by a motor 34. With this arrangement, rotation of the motor 34 in one direction will cause the lance 18 to be elevated, while rotation of the motor 34in the opposite direction will cause the lance 18 to descend. While the embodiment of the invention shown in FIG. 1 utilizes a cable 26, it should be understood that a chain and sprockets could be used equally as well, the essential requirement being that the hoist line 26 be of sufficient strength and flexibility to support the lance l8 and pass over the sheaves 28 and 30. Note that between the sheaves 28 and 30 the hoist line 26 extends along a generally horizontal reach 36 in FIG. 1. i

As was mentioned above, the control and drive motors for the lance 18 are controlled electrically and driven either by an electric motor or a fluid motor (i.e., pneumatic orhydraulic). Hence, if there should be a power failure, thelance 18 cannot be withdrawn by the conventional operating-equipment. It is, of course, possible to provide standby equipment which is not dependent upon the main power supply; however this is expensive, must be checked frequently, and is not altogether foolproof. If the oxygen or water flow to the lance should cease for some reason or other, the intense heat of the bath 12 .will damage or possibly destroy the lower end of the lance 18.

In accordance with the present invention, means are provided for automatically elevating the lance out of the vessel 10 upon the occurrence of a power failure, which means includes a weight 38 having rollers 41 which guide italongvertical guideways 42 and 44. The weight 38, in ,tum, is connected through a clevis 46 to a sheave 40 which rests on top of the hoist line 26 along the horizontal reach 36, the arrangement being such that should the weight 38 fall, the sheave 40. will move downwardly. However, before the sheave 40 and weight 38 are effective to hoist the lance 18, the drum 32 must be locked against rotation. Accordingly, the motor 34, which is mechanically connected to the drum 32, is provided with a brake 48 which will become engaged automatically upon the occurrence of a power failure, thereby locking the drum 32 against rotation. From the foregoing, it will be appreciated that if the drum 32 is locked against rotation and the weight 38 falls into the dotted line position shown, the lance 18 must move upwardly.

The weight 38 is normally held in its uppermost position shown by means of a latch 50 which fits'into a notch 52 in the side of the weight 38 and is held in that position by means ofa solenoid 54. A spring 56 tends to urge the latch 50 out of the notch 52; however when the solenoid 54 is energized, the force of the spring is overcome and the latch 50 is inserted into the notch 52 to hold the weight 38 in its elevated position shown.

NOrmally, the motor 34 is controlled by a conventional motor control circuit 33. The solenoid 54 is energized by the main plant electrical supply system58, as is the motor 34. Likewise, the brake 48 is held in its releasedposition by the same source of power. lf this source of power should fail for some reason or other, the brake 48 will be applied automatically to brake the drum 32 against rotatiomAt the :same time, deenergization of the solenoid 54,will cause the spring 56 to move the latch 50 out of notch 52, thereby permitting the weight 38 to drop downwardly and causing the lance 18 to move upwardly out of the vessel In FIG. 2, an alternative embodiment of the invention is shown which is similar to that of FIG. 1, except that the vertical movement of weight 38 is translated into horizontal movement to elevate the lance under emergency conditions. Accordingly, elements in F [G' 2 which corresponds to those of FIG. 1 are identified by like reference numerals.

Instead of deflecting the horizontal reach 36 of the cable as in FIG. 1, the weight 38 in FIG. 2 is connected to a cable or chain 60 which passes around sheave 62 and is connected at its other end to a sheave 64 reciprocable along horizontal tracks 66. The sheave 64 engages, at its'periphery, the right side of the cable 26 along its vertical reach between drum 32 and sheave 30. When the weight 38 falls under the conditions described in connection with FIG. 1, the sheave 64 will move to the left on tracks 66, thereby causing the cable to be pulled inwardly to the broken line position 68. This, of course, elevates the lance 18. The reach of cable 26 engaged by the movable sheave could be at an angle other than vertical or horizontal or could be partially deflected with the weight 38 in its uppermost position.

It is thus apparent that the present invention provides foolproof means for insuring removal of an oxygen lance from a basic oxygen converter upon the occurrence of a power failure, the system being dependent on gravity only. Although the invention has been shown in connection with a certain specific embodiment, it will readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention.

I claim as my invention:

1. In a system for manipulating a vertically reciprocable, water-cooled oxygen lance for a basic oxygen converter of the type wherein the lance is connected to a flexible hoist line which passes around rotary sheavelike devices to a'driven drum connected to a drive motor; the improvement comprising an element for engaging said hoist line at a point between said lance and driven drum, a weight adapted to move downwardly under the force of gravity and connected to said element whereby downward movement of the weight with said driven drum braked will cause said element to pull said hoist line transversely of its normal path of travel into a generally V shaped configuration to cause the lance to move upwardly, latch means for normally holding said weight in an elevated position, and means for unlatching said latch device and permitting said weight to fall downwardly to elevate said lance.

2. The system of claim I wherein said element comprises a rotary sheavelike device which engages a normally straightline reach of said hoist line and is connected to said weight through a clevis.

3. Thcsystem of claim 1 wherein said means for unlatching is actuated by an electrical power failure.

4. The system of claim 3 including a brake for said driven drum, and means for engaging said brake to prevent rotation of said drum upon the occurrence of a power failure when said latch means is unlatched.

5. The system of claim 3 wherein said latch meansis normally held in a latching position to prevent said weight from moving downwardly by an electrical solenoid supplied with power from a main power supply source.

6. The system of claim 1 wherein said hoist line comprises a cable.

7. The system of claim 2 wherein said reach extends horizontally between a pair of sheavelike devices and said lastmentioned sheavelike device engages the top of said reach.

8. The system of claim 7 wherein said weight is directly below said last-mentioned sheavelike device.

9. The system of claim 2 wherein said reach extends vertically and said weight is connected to said last-mentioned sheavelike device through a hoist line extending around another sheave device. 

1. In a system for manipulating a vertically reciprocable, water-cooled oxygen lance for a basic oxygen converter of the type wherein the lance is connected to a flexible hoist line which passes around rotary sheavelike devices to a driven drum connected to a drive motor; the improvement comprising an element for engaging said hoist line at a point between said lance and driven drum, a weight adapted to move downwardly under the force of gravity and connected to said element whereby downward movement of the weight with said driven drum braked will cause said element to pull said hoist line transversely of its normal path of travel into a generally V-shaped configuration to cause the lance to move upwardly, latch means for normally holding said weight in an elevated position, and means for unlatching said latch device and permitting said weight to fall downwardly to elevate said lance.
 2. The system of claim 1 wherein said element comprises a rotary sheavelike device which engages a normally straight-line reach of said hoist line and is connected to said weight through a clevis.
 3. The system of claim 1 wherein said means for unlatching is actuated by an electrical power failure.
 4. The system of claim 3 including a brake for said driven drum, and means for engaging said brake to prevent rotation of said drum upon the occurrence of a power failure when said latch means is unlatched.
 5. The system of claim 3 wherein said latch means is normally held in a latching position to prevent said weight from moving downwardly by an electrical solenoid supplied with power from a main power supply source.
 6. The system of claim 1 wherein said hoist line comprises a cable.
 7. The system of claim 2 wherein said reach extends horizontally between a pair of sheavelike devices and said last-mentioned sheavelike device engages the top of said reach.
 8. The system of claim 7 wherein said weight is directly below said last-mentioned sheavelike device.
 9. The system of claim 2 wherein said reach extends vertically and said weight is connected to said last-mentioned sheavelike device through a hoist line extending around another sheave device. 